Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (33권5호 373-380)

Effects of morphology and structure of electrolytic tin coating layers on the flow melting behaviors during reflow treatment

리플로우과정의 용융 거동에 미치는 전기주석 도금층의 결정 형상 및 구조의 영향

김태엽;조준형;이재륭;배대철;홍기정;

포항종합제철주식회사 기술연구소 표면처리연구그룹;포항산업과학연구원 재료물성분석팀;

Abstract

The flow melting behavior of the electrolytic tinplate during reflow treatment was investigated in terms of morphology and structure of coating layers which were electrodeposited with variation of electrolyte temperature. It was commonly found that the nucleation density of the electrodeposits showed little difference with the electrolyte temperature, and the growth of electrodeposited tin occurred along <100> direction of (002) plane. At low electrolyte temperature, the (002) plane of tin nucleated paralleling to the substrate and grew perpendicularly to the substrate, which rendered porous rod-like deposits. With increasing the temperature, the (002) plane nucleated declining $15^{circ}$ to the substrate and also grew to the normal <100> direction, which enabled lateral growth of the tin crystals and rendered compact deposits. During reflow treatment, the matte deposit transformed to the reflowed state via transition regions consisted of contraction, island formation, and wetting . The matte deposits formed at low temperature exhibited wide transition regions because of poor thermal transfer between crystals due to their porous nature. While that formed at high temperature transformed very rapidly to the reflowed state by enhanced thermal transfer between the compact crystals.

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